Refactor build wheels workflow to build against arbitrary libtiledb refs

[kounelisagis]

Following TileDB-Inc/TileDB#5691, this PR enables the wheel-build workflow of TileDB-Py to build directly against a libtiledb ref. This is extremely helpful for testing purposes.

Closes CORE-432

[ypatia]

Approving assuming that you have tested this and it works as expected.

[kounelisagis]

I reduced the scope of this PR so that it only affects the build wheels workflow and not the CI. That's because it would be a better idea to run the CI workflow against a libtiledb build from source (only if the user needs that), instead of building new libtiledb artifacts.

[kounelisagis]

Workflow run manually: https://github.com/TileDB-Inc/TileDB-Py/actions/runs/19641795832

using

gh workflow run build-wheels.yml --ref agis/workflows-libtiledb-ref \
    -f version=0.1.0 \
    -f libtiledb_ref=2.29.1

gives:

>>> import tiledb
>>> tiledb.libtiledb.version()
(2, 29, 1)
>>> tiledb.version()
(0, 1, 0)

✅